Direct exchange was limited. The pattern of indirect exchange led to the common medium of exchange: money. Maximization of psychic income always leads the seller of a good to seek the highest money price for it, and the buyer of a good to seek the lowest money price.
Entrepreneurs see the future better than others and go and make money off it. Profits are an index that maladjustments are being met and combatted by the profit-making entrepreneurs. Capital does not beget profits. Only wise entrepreneurial decisions do that.
Rothbard's approach to money prices is not as a barter exchange system. Instead, he made money prices the common denominator for all exchange ratios. You can now engage in economic calculation.
Here Rothbard deals with the pure rate of interest, as determined by time preference. It's a ratio of prices between present and future goods. The interest rate is equal to the rate of price spread in the various stages of production. It pervades all time markets.
Leading Austrian Economists discuss Henry Hazlitt's classic book Economics in One Lesson. Interview 1 of 12.
Human action is defined simply as purposeful behavior. Men act by virtue of their being human. Action can be undertaken only by individual actors. Leisure is a good. Mises derives economic law from this axiom that the study of man is the concept of action.
Exchange is the foundation of the division of labor. Each party to an exchange must expect greater psychic benefit than what he is giving up. Thus, trades are not equal, they are win-win activities. Property and ownership are value-free and a pre-condition of a free market.
